#define _CRT_SECURE_NO_WARNINGS 1
/********** Begin **********/
#include <stdio.h>
#include <math.h>
int main()
{
    float a = 0, b, k = 0, l;
    int m;
    scanf("%d", &m);
    for (int i = 1; i <= m; i++)
    {
        a++;
        b = log(a);
        k += b;
    }
    l = sqrt(k);
    printf("s = %lf", l);
    return 0;
}




/********** End **********/